The present invention relates to components for thermostatic units (of the kind used in thermostatic systems with a bimetallic element for environments or technical systems or in thermal protection relays for low-voltage circuit breakers), particularly to bimetallic elements and their connections to other components of said thermostatic units, and to a method for producing them. In particular, the present invention relates to a method for joining the bimetallic elements to other components of the thermostatic units by means of a laser welding process.
In low-voltage circuit breakers in the current art, the bimetallic element can generally be joined to the other components of thermostatic units, for example braids or terminal connection elements of a thermostat or the moving contacts of a circuit breaker, by mechanical coupling or by braze welding.
The mechanical joining of said bimetallic elements is performed traditionally by using rivets, nails, pressure-based systems or similar joining systems. Although this method provides an efficient joining system, it has drawbacks. In particular, electrical conductivity proximate to the contact points is not ideal and can vary among parts. Furthermore, the mechanical joining operation still requires a larger number of parts (for example rivets or nails) than strictly required for the functionality of the thermostatic unit, thus introducing complications in the assembly process and entailing in any case an increase in production costs.
As an alternative to mechanical coupling, the bimetallic element and the other components of the thermostatic units can be joined by virtue of conventional braze welding processes. These methods do not entail the drawbacks noted above, but entail other different ones, linked to the considerable application of heat required by this technology. As is known, the application of heat is a critical element in the welding of bimetallic elements, since it can entail structural variations of said bimetallic element. Accordingly, its performance is reduced, and therefore the number of substandard parts increases and in any case the behavior is uneven among parts.
It is evident, from what has been described above, that the current art needs to have components of thermostatic units that have a uniform behavior and can be manufactured efficiently. It is also evident that the current art needs to have an efficient method for joining components of thermostatic systems and thermal relays for low-voltage circuit breakers and particularly for joining bimetallic elements to the other components of the corresponding thermostatic units.
The aim of the present invention is to provide components of thermostatic units that can be manufactured efficiently and have a uniform behavior.